presence of otoacoustic emissions in profoundly deaf child (fwd)

Jeff Sirianni sirianni at UTS.CC.UTEXAS.EDU
Thu Sep 21 22:03:19 EST 1995


Date: Mon, 18 Sep 95 11:26:17 -0700
From: Kelley Mascher <mascher at u.washington.edu>
Subject: Re: presence of otoacoustic emissions in profoundly deaf child (fwd)

Hard walled calibration chambers are not at all like ear canals from an
emissions point of view. It is really more a matter of matching the 
acoustic impedance of the ear canal not just the volume. For adults
we use a Zwislocki coupler which is partially successfull but no infant
version exists. 

The best solution continues to be to lower the stimulus level and see
what happens to the response .Since the emission has a non-linear
amplitude response it should decrease significantly less than the
decrease in stimulus. If the response is an artifact it will decrease
with almost exactly the same as the stimulus.

David Kemp has a research system which measures DP and DP latency at the 
same time. This performs a similar function in that, an  artifactual DP 
has no time delay where a physiologically generated one must.

Kelley Mascher                                            (206) 528-2713
Children's Hospital & Med. Center               mascher at u.washington.edu
Audiology Research


In bionet.audiology you write:
>To Kelly : If this is the case, would it be practical to test one's equipment
>in a calibration chamber (i.e. 2 cc) to see if acoustic DP's arise due to
>transducer overload?  I understand that in a 16-month old one would want a
>smaller chamber...

>Thanks go to Allison Scott for bringing up this topic....

>Jeff Sirianni     @(((<{
>University of Texas at Austin
>Communication Sciences and Disorders
>CMA, 2nd Floor Clinic
>Austin, TX  78712-1089
>sirianni at uts.cc.utexas.edu
>jgsaudio at aol.com




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